Local high frequency coils with high frequency antennae are used to detect high frequency signals and/or magnetic resonance signals for magnetic resonance examinations in combination with a positron emission tomography examination (PET examination). In the case of the combination of magnetic resonance examinations with PET examinations, optimally accurate knowledge of a position and/or arrangement and/or geometry of the high frequency coils is required in order to exactly determine a signal attenuation which photons of a PET examination undergo as they pass through the high frequency coils. If high frequency coils are not taken into account in the attenuation correction, this can lead to absent PET events in the PET data and/or to image artifacts in the reconstructed image data. There is the difficulty, however, in the attenuation correction of high frequency coils that the local high frequency coils can be arranged on the patient at different positions and are often flexible and/or pliable. High frequency coils therefore often have an unknown geometry and/or unknown arrangement and/or unknown position.